PROJECT SUMMARY The meniscus fibrocartilage in the knee plays an essential role in load distribution, congruency, and joint stability, and is therefore necessary for proper joint biomechanics. Meniscus tears are the most frequent type of knee injury in active younger adults. Successful repair of tears decreases the development of osteoarthritis and subsequent need for joint replacement. Synthetic scaffolds have been developed to address segmental tissue defects; however, midterm outcomes have shown high failure rates and progression of chondral wear. The ultimate goal of this research is to develop a novel, long-lasting treatment for meniscus tears that shifts the treatment paradigm from one of removal of tissue to one of regeneration and preservation of function. In this application, our objective is to adopt a computationally assisted bioengineering approach to repair meniscal defects. We hypothesize that a scaffold closely mimicking structure, composition, biomechanics, transport, and electrokinetics of the healthy native tissue will integrate into the meniscus and will regenerate meniscal tissue at the defect. While some biomechanical properties of the meniscus have been investigated, little is known about meniscal transport and elektrokinetic properties, which are key determinants of cellular behavior and related tissue homeostasis. Using our expertise in electromechanics, transport and computational modeling of cartilaginous tissues, we will develop a novel library of design criteria, based on human meniscus properties (Aim 1). This will allow us to provide new structure-function relations for tissue properties in relation to biochemical composition and structural organization of the tissue. Based on this new knowledge, we will develop a new computational tool to evaluate the mechano-electrochemical environment (MEC) in meniscus tissues (Aim 2). Then, we will simulate the presence of meniscal defects repaired with tissue engineered scaffolds. We will investigate the effect of structural and compositional properties of the scaffold on MEC signals in order to identify optimal ranges of such parameters to recapitulate electromechanics and functional behavior of the native meniscal tissue. This will allow us to formulate initial design criteria for our novel scaffold, which will be further refined via an iterative process; at each iteration, (1) MEC properties of the scaffold will be measured and compared to those of the native tissue and, if necessary, (2) the design parameters of the scaffold will be tuned/improved as per indications of the computational model (Aim 3). Finally, we will seed meniscus fibrochondrocytes in the scaffold and integrate it into a meniscus defect using an ex vivo defect model. The scaffold?s biomechanical properties, cellular activity/viability post-culture and integration into a meniscus defect will be assessed and compared to those of a commercially available synthetic scaffold for meniscus repair. We present an innovative approach for bioengineering scaffolds for meniscus repair. Our rationally designed scaffold will provide an ideal environment for meniscus cells, which will translate to successful integration and regeneration of meniscus tissue at the defect, giving this project high potential for clinical translation.